Grand Blue Dreaming manga volume 18 features story by Kenji Inoue with art by Kimitake Yoshioka.

Nanaka is left fuming after she learns that Chisa lied to her about traveling to Okinawa. Suspecting Iori of seducing her sister during the trip, the frighteningly overprotective Nanaka plots how to make Iori come clean. Meanwhile, Iori finds his resolve floundering in the face of Sakurako’s relentless love attack. Will he make it out of this in one piece?